ABSTRACT
In this work we study magnetic properties of nanomagnets with lateral dimensions 50-100 nm. These structures have a potential of producing static memories with high storage densities. If simple disk is used as basic nanomagnet, its chirality and polarity cannot be read/write easily by in-plane magnetic field. Based on micromagnetic calculations, we have designed "Pac-man-like" (PL) nanomagnet and calculated its magnetic properties using the oommf code. It solves the micromagnetic problem using the Landau-Lifshitz-Gilbert equation. The calculations have shown, that in the PL shape both, the chirality and the polarity, can be controlled by the in-plane magnetic field with x, y components. The PL shape opens straight channel for the energy relaxation towards stable vortex state with defined chirality and polarity for thickness 32-48 nm, and diameter 50-78 nm.
ABSTRACT
Using micromagnetic calculations we search for optimal magnetic properties of novel magnetic tips to be used for a Switching Magnetization Magnetic Force Microscopy (SM-MFM), a novel technique based on two-pass scanning with reversed tip magnetization. Within the technique the sum of two scans images local atomic forces and their difference maps the local magnetic forces. The tip magnetization is switched during the scanning by a small magnetic field. The technology of novel low-coercitive magnetic tips is proposed. For best performance the tips must exhibit low magnetic moment, low switching field, and single-domain state at remanence. Such tips are equipped with Permalloy objects of a precise shape that are defined on their tilted sides. We calculate switching fields of such tips by solving the micromagnetic problem to find the optimum shape and dimensions of the Permalloy objects located on the tips. Among them, hexagon was found as the best shape for the tips.
ABSTRACT
We developed a technology of sub-micrometer Hall probes for future application in scanning hall probe microscopy (SHPM) and magnetic force microscopy (MFM). First, the Hall probes of approximately 9-mum dimensions are prepared on the top of high-aspect-ratio GaAs pyramids with an InGaP/AlGaAs/GaAs active layer using wet-chemical etching and non-planar lithography. Then we show that the active area of planar Hall probes can be downsized to sub-micrometer dimensions by local anodic oxidation technique using an atomic force microscope. Such planar probes are tested and their noise and magnetic field sensitivity are evaluated. Finally, the two technologies are combined to fabricate sub-micrometer Hall probes on the top of high-aspect ratio mesa for future SHPM and MFM techniques.
